Approximately 60,000 drug stores in the United States and 350,000 worldwide dispense prescription medications to patients each day. At the point of sale, tablets and capsules are stored in larger bulk quantities, and are then counted, packaged into smaller containers, labeled for use, and distributed to customers.
The classical tool for counting pills is the manual pill counting tray, and its use requires hand dexterity and the concentration of the user. To use, the user first deposits an unknown quantity of pills from a bulk-stock container onto the counting surface (platform) of a pill counting tray. Then, a spatula is used to move pills in uniformly sized groups of typically five pills each from this surface into an adjoining depressed trough region. Pills moved in this way are destined for dispensation; therefore the user is required to remember the changing count of pills reaching the trough throughout the counting process. Once the quantity of pills in the trough reaches the desired prescription quantity, the user closes a lid that blocks further pills from being deposited into the trough. By tilting the counting tray, the user returns excess pills from the platform surface back into the bulk-stock container. By tilting the tray in a different direction, counted pills are released through a funnel-shaped region in the trough into a prescription package, vial, bottle or the like. Throughout the day, this process may be repeated several hundred times at any one pharmacy. A testament to the manual counting tray's utility is that it has widely been used throughout the world for decades and is still used extensively by pharmacists today.
The manual pill counting tray's virtues include its straightforward operation, compact size, low cost, universal applicability to pills of varying shapes and sizes, easy cleanability, durability, and reputation as a time-honored standard for pill dispensation. In addition, as pills may be damaged, it offers an opportunity for the users to visually assess the pills as they are counted.
Nevertheless, the manual pill counting tray has drawbacks that include accuracy limited to the capability of the human user and concomitant limitations in speed of use. Reliance on human vision and memory as a means of counting is inherently error-prone, resulting in counting error at a rate of approximately 1 in 24 pills in the retail pharmacy setting. This inaccuracy can further be explained by distractions, such as telephone calls or customer interactions that may disrupt the concentration of the user while counting. The process is itself fatiguing, thus increasing the likelihood of user errors.
Though electronic and technologically sophisticated systems for dispensing pills are becoming increasingly more common, costs associated with these systems typically restrict their use to a limited subset of high-volume therapeutics. Examples of these systems include the Rx-4 pill counter sold by Rx Count Corporation (17945 Sky Park Circle, Ste. B; Irvine, Calif. 92614) and the KL1 automated pill counter produced by Kirby Lester, LLC (13700 Irma Lee Court, Lake Forest, Ill. 60045). Both of these systems employ optical scanning to count a stream of pills that pass through them. The pills to be counted by Rx-4 are poured onto a motor driven horizontally orientated table that rotates. The mechanics of this system limit the movement to one pill at a time past an optical scanner. In contrast, the KL1 is known as a “pour through” counting system. It has a small hopper at the top into which the pills to be counted are poured (see U.S. Pat. No. 6,497,339). By using a sprinkling technique to transfer pills from typically a bulk-storage container into the hopper, a limited stream of pills falls through a small opening at the bottom of the hopper and proceeds past a sophisticated optical scanner that can detect and count both single pills and small groups of pills, as described in U.S. Pat. No. 5,768,327. These systems, which cost in the range of several thousand dollars each, are not optimally suited to the highly variable requirements of individually dispensed medications in the retail environment where inventory levels and costs must be controlled. They also require a substantially higher level of operator training for use and maintenance.
One particular aspect of maintenance is that of cleaning the surfaces of the pill counting devices to avoid cross-contamination of residues that may be left after counting of one type of pill before counting another type having different chemistry. Such cleaning is necessary to avoid possible harm to patients using the counted pills. Clearly, cleaning the open platform and trough surfaces of a manual pill counting tray is less complicated than cleaning a rotating table and associated moving mechanical parts or cleaning the inside of a hopper, internal optics, and multifaceted receptacle container.
In addition to expensive counting systems such as the ones described above, there have been two prior attempts to semi-automate the traditional pill counting tray. Neither has yet experienced commercial success. The first is an optical based counting system described in U.S. Pat. No. 6,574,580 PHARMACY PILL COUNTING VISION SYSTEM, that will be referred to as Hamilton '580, and the second is a weight-based counting system described in U.S. Pat. No. 8,530,763 COUNTING SCALE AND METHOD OF COUNTING INVOLVING DETERMINATION OF SUBMULTIPLES BY MEANS OF A SERIES OF DIVISORS, referred to as Bradley '763.
While Hamilton '580 employs a somewhat conventional manual pill counting tray to place the pills being counted, it also requires an overhead digital camera having a field of view focused on the tray and a personal computer (PC) to process the camera's output signal and to display the count results. In addition, a special light source is normally used that can vary in color to improve the visual contrast of various colored pills placed in the tray. While the tray remains compact in size and low in cost, the entire optical based system is quite complex, considerably larger than only the tray, and non-trivial to keep in alignment. It is not surprising that this optical-based system may not be commercially competitive with the more established automatic systems like the ones previously described.
In contrast, the weight-based semi-automated tray counting system in Bradley '763 has the desirable features of being compact and presumably low in cost to manufacture. However, the tray modifications introduced by Bradley '763 do not support the design objective or capability of improving pill counting speed. Rather, the objective behind this invention is limited to enhancing pill counting accuracy. As stated in Bradley '763 “The device [pill counting tray] may have a display that can be made obscure in that the displayed, derived values [of pills counted] can be hidden from view to prevent its use as a primary count checker. For, example, a disclosed system places the display on the underside of a tray table where the results cannot be observed initially. Such an arrangement can be advantageous in the case of weighing pills, in that increased reliability will be obtained by forcing the pharmacy personnel to count the pills [manually] first and use the results of the automated weigh count process as ancillary.” This patent goes on to say “Since the device/method typically will be used for a cross check only, the need for an elaborate weighing device is eliminated. The same inexpensive plastic counting tray that is used today can be used, with the addition of a relatively inexpensive weighing capability.”
The inventive aspect of Bradley '763 is limited to a novel weight based electronic counting method that proceeds in parallel while the user is conducting a normal manual pill count. Specifically, as groups of pills are manually counted and transferred from the tray to the trough by the user, the weight of each group is also determined and then electronically processed. The inventive aspect of Bradley '763 is a novel method for determining the unit weight of the pills being transferred so that count of the total number of pills in the trough can be computed by dividing the total weight of all of the pills transferred to the trough by their unit weight without any user involvement.
According to Bradley '763 “The processing device is operable to programmatically apply a series of divisors to consecutive values of the [transferred group of pills'] weight signal in order to automatically discern submultiples in the consecutive values . . . . This produces a series of prospective unit weights for the first weighing, a series of prospective weights for the second weighing, third weighing, and so forth. Each of the series is searched to find unit values that substantially match, thereby producing at least one collection of count values, one count for each of the weightings.”
The reality of this rather complex calculation to determine the pill count is that it simply will not work if the user counts groups of, say, five pills at a time (which is typical for many manual users) because the processor will not be able to distinguish whether a single heavy pill or five lighter weight pills are being transferred from the platform to the trough. To obtain a satisfactory result using the methods taught by Bradley '763, the operator must be trained to transfer groups of pills having different total numbers so that the prospective weights for each group can be compared and, hopefully, identify a unique weight that is common to all of the groups. In the example discussed above, where the groups always consist of five pills, a unique weight will not be established for individual pills. Rather the pill weight will be either that of one pill or five pills. However if different numbers of pills are transferred in successive groups, such as 7, 12, and 11 pills, there would be a single prospective unit weight that would satisfy all three groups. This value would then be selected for the unit weight associated with all 30 pills (7+12+11) that were transferred.
It should be noted that in FIGS. 1, 4, and 5 of Bradley '763 the circuit board (116) where the microprocessor device is mounted is located directly under the flat platform area of the counting tray. The weighing device in Bradley '763 is typically located directly under this same flat platform so that in use the weight of any pills that are swept from the platform into the trough by the user (the normal operation of a manual counting tray) can be inferred by the reduction in the total weight of the pills on the platform. However, Bradley '763 also mentions that the weight sensor can also connect to the trough or two weight sensors may be employed, one for the platform and the other for the trough, to provide redundant determination of the weight. Yet in another embodiment, Bradley '763 mentions that four weight sensors can be used with one located in each of the four legs that support the tray's platform. In this case, the weight of the pills on the platform would be equal to the sum of the outputs from all four weight sensors. For satisfactory operation, there can be no mechanical connection between the platform and the trough. Otherwise, there would be no detected weight change when pills are moved from the platform to the trough.
Bradley '763 also calls for a tilt sensor switch in all embodiments of this invention. This switch closes when the tray is set upon a counter or other horizontal surface. The closure is sensed by the microcontroller which then automatically initiates the electronic weighing sequence that automatically proceeds in parallel with manual counting by the user.
It is apparent from both the description and design of the device(s) in Bradley '763 that the objective is to improve pill counting accuracy and that no consideration has been given to improving pill counting speed. It would, of course, be desirable to simultaneously improve both pill counting accuracy and pill counting speed if that were possible because greater speed would save time for the user and that savings could be translated into a financial benefit. However, there has been no prior effort to add an inexpensive weight-based counting capability to semi-automate a pill counting tray to improve both counting accuracy and pill counting speed. In fact, it is not obvious that both of these goals can be simultaneously achieved due to a number of uncertain factors including: (1) Sufficient weight variation from pill to pill such that there may be no way to ensure an accurate count. This variation could be caused by abrasions of pills, less that 100% homogeneity of the pill's material, moisture pick-up by the pills from variable ambient humidity, and dust from pills that may be inadvertently transferred from the counting platform to the trough in uncontrolled amounts when the user transfers a group of pills. (2) The possibility of overfilling the trough so that large pill counts (say 90 or more) would require more than a single counting sequence and thereby slow down the counting speed to the point where the entire semi-automatic counting process becomes less efficient. (3) The difficulty of making the weighing device sufficiently linear in response and insensitive to ambient air currents and pressure waves and stray electrostatic fiends so that weight of both small and large numbers of pills can be accurately determined without elaborate or complex scale designs that would make the manufacturing cost excessive. (4) The possibility that higher speed pill counting could only be achieved with operating procedures that would be difficult for typical users to learn. (5) A pill counting tray that would be awkward for a user to lift to pour counted pills into a prescription container and uncounted back into a bulk-storage container. (6) The lack of prior art that might provide some guidance on feasibility and methods for improving pill counting speed with a semi-automated pill counting tray.
When considering all of these factors, one is left with uncertainty and related risk of failure for anyone desiring to improve both pill counting accuracy and speed by attempting to semi-automate a manual pill counting tray. Nevertheless, it is expected that a success in this area would be broadly welcomed by pharmacists throughout the world.
See also U.S. Pat. Nos. 4,512,428; 4,738,324; 4,646,767; 4,802,541; 4,856,603; 5,473,703; 6,738,723; 7,633,018; 8,271,128; 8.464,765; and U.S. Pub No. 2008/0011764.